So many young people (especially athletes) injure their anterior cruciate ligament (ACL), it has become a major concern among sports health professionals. Girls and women seem to be at greater risk than their male counterparts. Much research has gone into trying to understand the risk factors in order to prevent this potentially disabling injury.
Research has shown us there are many potential risk factors for ACL injuries. These are broken down into two distinct groups: intrinsic and extrinsic factors. Intrinsic refers to something within us such as the effect of hormones, genetics, and cognitive factors that might contribute to anterior cruciate ligament injuries.
Extrinsic factors (outside ourselves) include previous injury and other things like the weather, shoe wear, playing surface, time of year, indoor versus outdoor play, and even the amount of rainfall for outdoor events.
With females it’s easy to think the major difference is hormonal and look for a connection with the menstrual cycle. Some studies have attempted to see if females are more likely to injure their knees at a particular time in the menstrual cycle. It’s also possible the risk is no different over the course of time for females. But due to a variety of study designs and differing ways of analyzing the data, no consensus or agreement has been made.
Scientists have discovered receptor sites on the anterior cruciate ligament (ACL) for hormones such as estrogen and progesterone. Just the presence of these places for hormones to attach to cells suggests hormones may influence ligaments. But what the connection is or exactly how these hormones affect the ACL is a big unknown right now.
There may be some anatomic reasons for this. For example, women have a different shape to the bone structure forming the knee. The female ACL is more elastic and less stiff than the male ACL. Female athletes move differently than male athletes and with that difference comes a difference in muscle activation patterns.
The area of genetics is still being researched. Genetic factors associated with ACL tears have been identified in two studies. There are specific genes associated with ACL tears but these are considered rare. Observations that family members often share similar ACL injuries have led to some studies to examine this more closely. It appears that there is a much higher rate of ACL tears in family members of those who have been injured. So your family situation may reflect those findings as well.
It’s highly likely there are multiple factors involved in ACL injuries among females. Whether this is a combination of intrinsic factors, extrinsic factors, or both remains to be proven. More studies are needed to really examine each of these factors individually and also when combined together in different ways. With more information about risk factors, it might be possible to screen athletes for risk and use prevention strategies to avoid such injuries.